IVIG Preparations
A total of 54 IVIG lots fractionated from plasma collected prior to the circulation of SARS-CoV-2 were analyzed. The IVIG lots were manufactured from plasma either donated by plasmapheresis (source) or recovered from whole-blood donations (recovered), in the United States (Gammagard Liquid; Baxter Healthcare Corp.; n = 30) or central Europe, that is Austria, Germany, and Czech Republic (KIOVIG; Baxter AG; n = 24). These 54 IVIG lots were tested in 2 independent experiments for nAbs (1 European lot was in a single assay due to volume constraints).